Several recent developments related to energy production and utilization have created increased need for storage of gases, especially efficient means of storing neutral hydrogen with high storage density. Such high storage density of hydrogen is required for effective functioning of fuel cells and is also important for other increasing uses of hydrogen gas in the national economy and in the world economy.
There are several ways to store neutral hydrogen at relatively high densities: tanks of compressed gas, dewars of liquid hydrogen, chambers containing metal hydrides, and others. Metal hydrides, while useful, have a problem of undesirable weight. The liquid form of hydrogen requires maintenance of very low temperatures. Storage of compressed gas uses high pressures. Thus, no ideal method is available at present, and development of alternative methods is desirable.
Physisorption of gas molecules on a solid surface is another phenomenon that may be exploited for gas storage. For that purpose, materials and media with large surface-to-volume ratios are required. Various media have been tried, including glass spheres and carbon nanotubes. While such media have performed the desired function, there is an ongoing need for gas storage media which have increased surface-to-volume ratios and gas storage capacity for neutral hydrogen and for other gas molecules.